ABSTRACTAcute leukemia is a malignant clonal hematopoietic stem cell disease. In the current study, the effects of arsenic trioxide (ATO) on the ecotropic viral integration site-1 (EVI-1) gene were investigated in the THP1 cell line. THP-1 cells were treated with different concentrations of ATO (0, 1, 3 and 5 μM) for 24, 48 or 72 h, then tested for cell viability by CCK-8 kit, cell morphology by cytospin smear, cell apoptosis by flow cytometry, EVI-1 mRNA expression by reverse transcription polymerase chain reaction (RT-PCR) and protein quantity by western blot. ATO treatment was shown to inhibit proliferation and induce apoptosis in THP1 cells in a dose- and time-dependent manner. ATO downregulated the mRNA and protein expression of EVI-1 in the THP1 cell line. In addition, ATO significantly decreased the expression of antiapoptotic proteins, B-cell lymphoma 2 (Bcl-2) and B cell lymphoma-extra large (Bcl-xL), but markedly increased the expression of proapoptotic proteins, including c-Jun N-terminal kinase (JNK), phosphorylated-JNK, Bax, full length caspase-3 and cleaved caspase-3. These results indicated that ATO inhibited the proliferation and induced apoptosis in THP1 cells partially via blocking the inhibitory effects of EVI-1 on the JNK signaling pathway with the involvement of apoptosis-associated proteins, including Bax, Bcl-2, Bcl-xL and caspase-3. These novel observations may be used to elucidate the mechanism by which ATO induces apoptosis in acute leukemia cells, and provide rationales to develop a personalized medicine strategy for ATO via targeting EVI-1 positive neoplasm.

Mentions:
Relative EVI-1 mRNA expression levels were measured in four leukemia cell lines, K562, HL-60, U937 and THP1. Expression levels were also measured in PBMCs from a healthy adult, which was used as a control. The mRNA expression of EVI-1 in the PBMCs from the healthy adult was very low. Among the four leukemia cell lines, THP1 cells exhibited the highest EVI-1 expression (Fig. 1). Thus, the THP1 cell line was selected for further study. Through gene sequencing analysis and comparison with Genbank, the THP1 cell line was confirmed to contain the full length of the EVI-1 gene with 21 exons (data not shown).

Mentions:
Relative EVI-1 mRNA expression levels were measured in four leukemia cell lines, K562, HL-60, U937 and THP1. Expression levels were also measured in PBMCs from a healthy adult, which was used as a control. The mRNA expression of EVI-1 in the PBMCs from the healthy adult was very low. Among the four leukemia cell lines, THP1 cells exhibited the highest EVI-1 expression (Fig. 1). Thus, the THP1 cell line was selected for further study. Through gene sequencing analysis and comparison with Genbank, the THP1 cell line was confirmed to contain the full length of the EVI-1 gene with 21 exons (data not shown).

Bottom Line:
In the current study, the effects of arsenic trioxide (ATO) on the ecotropic viral integration site-1 (EVI-1) gene were investigated in the THP1 cell line.In addition, ATO significantly decreased the expression of antiapoptotic proteins, B-cell lymphoma 2 (Bcl-2) and B cell lymphoma-extra large (Bcl-xL), but markedly increased the expression of proapoptotic proteins, including c-Jun N-terminal kinase (JNK), phosphorylated-JNK, Bax, full length caspase-3 and cleaved caspase-3.These results indicated that ATO inhibited the proliferation and induced apoptosis in THP1 cells partially via blocking the inhibitory effects of EVI-1 on the JNK signaling pathway with the involvement of apoptosis-associated proteins, including Bax, Bcl-2, Bcl-xL and caspase-3.

ABSTRACTAcute leukemia is a malignant clonal hematopoietic stem cell disease. In the current study, the effects of arsenic trioxide (ATO) on the ecotropic viral integration site-1 (EVI-1) gene were investigated in the THP1 cell line. THP-1 cells were treated with different concentrations of ATO (0, 1, 3 and 5 μM) for 24, 48 or 72 h, then tested for cell viability by CCK-8 kit, cell morphology by cytospin smear, cell apoptosis by flow cytometry, EVI-1 mRNA expression by reverse transcription polymerase chain reaction (RT-PCR) and protein quantity by western blot. ATO treatment was shown to inhibit proliferation and induce apoptosis in THP1 cells in a dose- and time-dependent manner. ATO downregulated the mRNA and protein expression of EVI-1 in the THP1 cell line. In addition, ATO significantly decreased the expression of antiapoptotic proteins, B-cell lymphoma 2 (Bcl-2) and B cell lymphoma-extra large (Bcl-xL), but markedly increased the expression of proapoptotic proteins, including c-Jun N-terminal kinase (JNK), phosphorylated-JNK, Bax, full length caspase-3 and cleaved caspase-3. These results indicated that ATO inhibited the proliferation and induced apoptosis in THP1 cells partially via blocking the inhibitory effects of EVI-1 on the JNK signaling pathway with the involvement of apoptosis-associated proteins, including Bax, Bcl-2, Bcl-xL and caspase-3. These novel observations may be used to elucidate the mechanism by which ATO induces apoptosis in acute leukemia cells, and provide rationales to develop a personalized medicine strategy for ATO via targeting EVI-1 positive neoplasm.